Mercurial > hg > truffle
diff src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp @ 342:37f87013dfd8
6711316: Open source the Garbage-First garbage collector
Summary: First mercurial integration of the code for the Garbage-First garbage collector.
Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr
author | ysr |
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date | Thu, 05 Jun 2008 15:57:56 -0700 |
parents | |
children | 58054a18d735 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp Thu Jun 05 15:57:56 2008 -0700 @@ -0,0 +1,1199 @@ +/* + * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +// A G1CollectorPolicy makes policy decisions that determine the +// characteristics of the collector. Examples include: +// * choice of collection set. +// * when to collect. + +class HeapRegion; +class CollectionSetChooser; + +// Yes, this is a bit unpleasant... but it saves replicating the same thing +// over and over again and introducing subtle problems through small typos and +// cutting and pasting mistakes. The macros below introduces a number +// sequnce into the following two classes and the methods that access it. + +#define define_num_seq(name) \ +private: \ + NumberSeq _all_##name##_times_ms; \ +public: \ + void record_##name##_time_ms(double ms) { \ + _all_##name##_times_ms.add(ms); \ + } \ + NumberSeq* get_##name##_seq() { \ + return &_all_##name##_times_ms; \ + } + +class MainBodySummary; +class PopPreambleSummary; + +class PauseSummary { + define_num_seq(total) + define_num_seq(other) + +public: + virtual MainBodySummary* main_body_summary() { return NULL; } + virtual PopPreambleSummary* pop_preamble_summary() { return NULL; } +}; + +class MainBodySummary { + define_num_seq(satb_drain) // optional + define_num_seq(parallel) // parallel only + define_num_seq(ext_root_scan) + define_num_seq(mark_stack_scan) + define_num_seq(scan_only) + define_num_seq(update_rs) + define_num_seq(scan_rs) + define_num_seq(scan_new_refs) // Only for temp use; added to + // in parallel case. + define_num_seq(obj_copy) + define_num_seq(termination) // parallel only + define_num_seq(parallel_other) // parallel only + define_num_seq(mark_closure) + define_num_seq(clear_ct) // parallel only +}; + +class PopPreambleSummary { + define_num_seq(pop_preamble) + define_num_seq(pop_update_rs) + define_num_seq(pop_scan_rs) + define_num_seq(pop_closure_app) + define_num_seq(pop_evacuation) + define_num_seq(pop_other) +}; + +class NonPopSummary: public PauseSummary, + public MainBodySummary { +public: + virtual MainBodySummary* main_body_summary() { return this; } +}; + +class PopSummary: public PauseSummary, + public MainBodySummary, + public PopPreambleSummary { +public: + virtual MainBodySummary* main_body_summary() { return this; } + virtual PopPreambleSummary* pop_preamble_summary() { return this; } +}; + +class NonPopAbandonedSummary: public PauseSummary { +}; + +class PopAbandonedSummary: public PauseSummary, + public PopPreambleSummary { +public: + virtual PopPreambleSummary* pop_preamble_summary() { return this; } +}; + +class G1CollectorPolicy: public CollectorPolicy { +protected: + // The number of pauses during the execution. + long _n_pauses; + + // either equal to the number of parallel threads, if ParallelGCThreads + // has been set, or 1 otherwise + int _parallel_gc_threads; + + enum SomePrivateConstants { + NumPrevPausesForHeuristics = 10, + NumPrevGCsForHeuristics = 10, + NumAPIs = HeapRegion::MaxAge + }; + + G1MMUTracker* _mmu_tracker; + + void initialize_flags(); + + void initialize_all() { + initialize_flags(); + initialize_size_info(); + initialize_perm_generation(PermGen::MarkSweepCompact); + } + + virtual size_t default_init_heap_size() { + // Pick some reasonable default. + return 8*M; + } + + + double _cur_collection_start_sec; + size_t _cur_collection_pause_used_at_start_bytes; + size_t _cur_collection_pause_used_regions_at_start; + size_t _prev_collection_pause_used_at_end_bytes; + double _cur_collection_par_time_ms; + double _cur_satb_drain_time_ms; + double _cur_clear_ct_time_ms; + bool _satb_drain_time_set; + double _cur_popular_preamble_start_ms; + double _cur_popular_preamble_time_ms; + double _cur_popular_compute_rc_time_ms; + double _cur_popular_evac_time_ms; + + double _cur_CH_strong_roots_end_sec; + double _cur_CH_strong_roots_dur_ms; + double _cur_G1_strong_roots_end_sec; + double _cur_G1_strong_roots_dur_ms; + + // Statistics for recent GC pauses. See below for how indexed. + TruncatedSeq* _recent_CH_strong_roots_times_ms; + TruncatedSeq* _recent_G1_strong_roots_times_ms; + TruncatedSeq* _recent_evac_times_ms; + // These exclude marking times. + TruncatedSeq* _recent_pause_times_ms; + TruncatedSeq* _recent_gc_times_ms; + + TruncatedSeq* _recent_CS_bytes_used_before; + TruncatedSeq* _recent_CS_bytes_surviving; + + TruncatedSeq* _recent_rs_sizes; + + TruncatedSeq* _concurrent_mark_init_times_ms; + TruncatedSeq* _concurrent_mark_remark_times_ms; + TruncatedSeq* _concurrent_mark_cleanup_times_ms; + + NonPopSummary* _non_pop_summary; + PopSummary* _pop_summary; + NonPopAbandonedSummary* _non_pop_abandoned_summary; + PopAbandonedSummary* _pop_abandoned_summary; + + NumberSeq* _all_pause_times_ms; + NumberSeq* _all_full_gc_times_ms; + double _stop_world_start; + NumberSeq* _all_stop_world_times_ms; + NumberSeq* _all_yield_times_ms; + + size_t _region_num_young; + size_t _region_num_tenured; + size_t _prev_region_num_young; + size_t _prev_region_num_tenured; + + NumberSeq* _all_mod_union_times_ms; + + int _aux_num; + NumberSeq* _all_aux_times_ms; + double* _cur_aux_start_times_ms; + double* _cur_aux_times_ms; + bool* _cur_aux_times_set; + + double* _par_last_ext_root_scan_times_ms; + double* _par_last_mark_stack_scan_times_ms; + double* _par_last_scan_only_times_ms; + double* _par_last_scan_only_regions_scanned; + double* _par_last_update_rs_start_times_ms; + double* _par_last_update_rs_times_ms; + double* _par_last_update_rs_processed_buffers; + double* _par_last_scan_rs_start_times_ms; + double* _par_last_scan_rs_times_ms; + double* _par_last_scan_new_refs_times_ms; + double* _par_last_obj_copy_times_ms; + double* _par_last_termination_times_ms; + + // there are two pases during popular pauses, so we need to store + // somewhere the results of the first pass + double* _pop_par_last_update_rs_start_times_ms; + double* _pop_par_last_update_rs_times_ms; + double* _pop_par_last_update_rs_processed_buffers; + double* _pop_par_last_scan_rs_start_times_ms; + double* _pop_par_last_scan_rs_times_ms; + double* _pop_par_last_closure_app_times_ms; + + double _pop_compute_rc_start; + double _pop_evac_start; + + // indicates that we are in young GC mode + bool _in_young_gc_mode; + + // indicates whether we are in full young or partially young GC mode + bool _full_young_gcs; + + // if true, then it tries to dynamically adjust the length of the + // young list + bool _adaptive_young_list_length; + size_t _young_list_min_length; + size_t _young_list_target_length; + size_t _young_list_so_prefix_length; + size_t _young_list_fixed_length; + + size_t _young_cset_length; + bool _last_young_gc_full; + + double _target_pause_time_ms; + + unsigned _full_young_pause_num; + unsigned _partial_young_pause_num; + + bool _during_marking; + bool _in_marking_window; + bool _in_marking_window_im; + + SurvRateGroup* _short_lived_surv_rate_group; + SurvRateGroup* _survivor_surv_rate_group; + // add here any more surv rate groups + + bool during_marking() { + return _during_marking; + } + + // <NEW PREDICTION> + +private: + enum PredictionConstants { + TruncatedSeqLength = 10 + }; + + TruncatedSeq* _alloc_rate_ms_seq; + double _prev_collection_pause_end_ms; + + TruncatedSeq* _pending_card_diff_seq; + TruncatedSeq* _rs_length_diff_seq; + TruncatedSeq* _cost_per_card_ms_seq; + TruncatedSeq* _cost_per_scan_only_region_ms_seq; + TruncatedSeq* _fully_young_cards_per_entry_ratio_seq; + TruncatedSeq* _partially_young_cards_per_entry_ratio_seq; + TruncatedSeq* _cost_per_entry_ms_seq; + TruncatedSeq* _partially_young_cost_per_entry_ms_seq; + TruncatedSeq* _cost_per_byte_ms_seq; + TruncatedSeq* _constant_other_time_ms_seq; + TruncatedSeq* _young_other_cost_per_region_ms_seq; + TruncatedSeq* _non_young_other_cost_per_region_ms_seq; + + TruncatedSeq* _pending_cards_seq; + TruncatedSeq* _scanned_cards_seq; + TruncatedSeq* _rs_lengths_seq; + + TruncatedSeq* _cost_per_byte_ms_during_cm_seq; + TruncatedSeq* _cost_per_scan_only_region_ms_during_cm_seq; + + TruncatedSeq* _young_gc_eff_seq; + + TruncatedSeq* _max_conc_overhead_seq; + + size_t _recorded_young_regions; + size_t _recorded_scan_only_regions; + size_t _recorded_non_young_regions; + size_t _recorded_region_num; + + size_t _free_regions_at_end_of_collection; + size_t _scan_only_regions_at_end_of_collection; + + size_t _recorded_rs_lengths; + size_t _max_rs_lengths; + + size_t _recorded_marked_bytes; + size_t _recorded_young_bytes; + + size_t _predicted_pending_cards; + size_t _predicted_cards_scanned; + size_t _predicted_rs_lengths; + size_t _predicted_bytes_to_copy; + + double _predicted_survival_ratio; + double _predicted_rs_update_time_ms; + double _predicted_rs_scan_time_ms; + double _predicted_scan_only_scan_time_ms; + double _predicted_object_copy_time_ms; + double _predicted_constant_other_time_ms; + double _predicted_young_other_time_ms; + double _predicted_non_young_other_time_ms; + double _predicted_pause_time_ms; + + double _vtime_diff_ms; + + double _recorded_young_free_cset_time_ms; + double _recorded_non_young_free_cset_time_ms; + + double _sigma; + double _expensive_region_limit_ms; + + size_t _rs_lengths_prediction; + + size_t _known_garbage_bytes; + double _known_garbage_ratio; + + double sigma() { + return _sigma; + } + + // A function that prevents us putting too much stock in small sample + // sets. Returns a number between 2.0 and 1.0, depending on the number + // of samples. 5 or more samples yields one; fewer scales linearly from + // 2.0 at 1 sample to 1.0 at 5. + double confidence_factor(int samples) { + if (samples > 4) return 1.0; + else return 1.0 + sigma() * ((double)(5 - samples))/2.0; + } + + double get_new_neg_prediction(TruncatedSeq* seq) { + return seq->davg() - sigma() * seq->dsd(); + } + +#ifndef PRODUCT + bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group); +#endif // PRODUCT + +protected: + double _pause_time_target_ms; + double _recorded_young_cset_choice_time_ms; + double _recorded_non_young_cset_choice_time_ms; + bool _within_target; + size_t _pending_cards; + size_t _max_pending_cards; + +public: + + void set_region_short_lived(HeapRegion* hr) { + hr->install_surv_rate_group(_short_lived_surv_rate_group); + } + + void set_region_survivors(HeapRegion* hr) { + hr->install_surv_rate_group(_survivor_surv_rate_group); + } + +#ifndef PRODUCT + bool verify_young_ages(); +#endif // PRODUCT + + void tag_scan_only(size_t short_lived_scan_only_length); + + double get_new_prediction(TruncatedSeq* seq) { + return MAX2(seq->davg() + sigma() * seq->dsd(), + seq->davg() * confidence_factor(seq->num())); + } + + size_t young_cset_length() { + return _young_cset_length; + } + + void record_max_rs_lengths(size_t rs_lengths) { + _max_rs_lengths = rs_lengths; + } + + size_t predict_pending_card_diff() { + double prediction = get_new_neg_prediction(_pending_card_diff_seq); + if (prediction < 0.00001) + return 0; + else + return (size_t) prediction; + } + + size_t predict_pending_cards() { + size_t max_pending_card_num = _g1->max_pending_card_num(); + size_t diff = predict_pending_card_diff(); + size_t prediction; + if (diff > max_pending_card_num) + prediction = max_pending_card_num; + else + prediction = max_pending_card_num - diff; + + return prediction; + } + + size_t predict_rs_length_diff() { + return (size_t) get_new_prediction(_rs_length_diff_seq); + } + + double predict_alloc_rate_ms() { + return get_new_prediction(_alloc_rate_ms_seq); + } + + double predict_cost_per_card_ms() { + return get_new_prediction(_cost_per_card_ms_seq); + } + + double predict_rs_update_time_ms(size_t pending_cards) { + return (double) pending_cards * predict_cost_per_card_ms(); + } + + double predict_fully_young_cards_per_entry_ratio() { + return get_new_prediction(_fully_young_cards_per_entry_ratio_seq); + } + + double predict_partially_young_cards_per_entry_ratio() { + if (_partially_young_cards_per_entry_ratio_seq->num() < 2) + return predict_fully_young_cards_per_entry_ratio(); + else + return get_new_prediction(_partially_young_cards_per_entry_ratio_seq); + } + + size_t predict_young_card_num(size_t rs_length) { + return (size_t) ((double) rs_length * + predict_fully_young_cards_per_entry_ratio()); + } + + size_t predict_non_young_card_num(size_t rs_length) { + return (size_t) ((double) rs_length * + predict_partially_young_cards_per_entry_ratio()); + } + + double predict_rs_scan_time_ms(size_t card_num) { + if (full_young_gcs()) + return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); + else + return predict_partially_young_rs_scan_time_ms(card_num); + } + + double predict_partially_young_rs_scan_time_ms(size_t card_num) { + if (_partially_young_cost_per_entry_ms_seq->num() < 3) + return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); + else + return (double) card_num * + get_new_prediction(_partially_young_cost_per_entry_ms_seq); + } + + double predict_scan_only_time_ms_during_cm(size_t scan_only_region_num) { + if (_cost_per_scan_only_region_ms_during_cm_seq->num() < 3) + return 1.5 * (double) scan_only_region_num * + get_new_prediction(_cost_per_scan_only_region_ms_seq); + else + return (double) scan_only_region_num * + get_new_prediction(_cost_per_scan_only_region_ms_during_cm_seq); + } + + double predict_scan_only_time_ms(size_t scan_only_region_num) { + if (_in_marking_window_im) + return predict_scan_only_time_ms_during_cm(scan_only_region_num); + else + return (double) scan_only_region_num * + get_new_prediction(_cost_per_scan_only_region_ms_seq); + } + + double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) { + if (_cost_per_byte_ms_during_cm_seq->num() < 3) + return 1.1 * (double) bytes_to_copy * + get_new_prediction(_cost_per_byte_ms_seq); + else + return (double) bytes_to_copy * + get_new_prediction(_cost_per_byte_ms_during_cm_seq); + } + + double predict_object_copy_time_ms(size_t bytes_to_copy) { + if (_in_marking_window && !_in_marking_window_im) + return predict_object_copy_time_ms_during_cm(bytes_to_copy); + else + return (double) bytes_to_copy * + get_new_prediction(_cost_per_byte_ms_seq); + } + + double predict_constant_other_time_ms() { + return get_new_prediction(_constant_other_time_ms_seq); + } + + double predict_young_other_time_ms(size_t young_num) { + return + (double) young_num * + get_new_prediction(_young_other_cost_per_region_ms_seq); + } + + double predict_non_young_other_time_ms(size_t non_young_num) { + return + (double) non_young_num * + get_new_prediction(_non_young_other_cost_per_region_ms_seq); + } + + void check_if_region_is_too_expensive(double predicted_time_ms); + + double predict_young_collection_elapsed_time_ms(size_t adjustment); + double predict_base_elapsed_time_ms(size_t pending_cards); + double predict_base_elapsed_time_ms(size_t pending_cards, + size_t scanned_cards); + size_t predict_bytes_to_copy(HeapRegion* hr); + double predict_region_elapsed_time_ms(HeapRegion* hr, bool young); + + // for use by: calculate_optimal_so_length(length) + void predict_gc_eff(size_t young_region_num, + size_t so_length, + double base_time_ms, + double *gc_eff, + double *pause_time_ms); + + // for use by: calculate_young_list_target_config(rs_length) + bool predict_gc_eff(size_t young_region_num, + size_t so_length, + double base_time_with_so_ms, + size_t init_free_regions, + double target_pause_time_ms, + double* gc_eff); + + void start_recording_regions(); + void record_cset_region(HeapRegion* hr, bool young); + void record_scan_only_regions(size_t scan_only_length); + void end_recording_regions(); + + void record_vtime_diff_ms(double vtime_diff_ms) { + _vtime_diff_ms = vtime_diff_ms; + } + + void record_young_free_cset_time_ms(double time_ms) { + _recorded_young_free_cset_time_ms = time_ms; + } + + void record_non_young_free_cset_time_ms(double time_ms) { + _recorded_non_young_free_cset_time_ms = time_ms; + } + + double predict_young_gc_eff() { + return get_new_neg_prediction(_young_gc_eff_seq); + } + + // </NEW PREDICTION> + +public: + void cset_regions_freed() { + bool propagate = _last_young_gc_full && !_in_marking_window; + _short_lived_surv_rate_group->all_surviving_words_recorded(propagate); + _survivor_surv_rate_group->all_surviving_words_recorded(propagate); + // also call it on any more surv rate groups + } + + void set_known_garbage_bytes(size_t known_garbage_bytes) { + _known_garbage_bytes = known_garbage_bytes; + size_t heap_bytes = _g1->capacity(); + _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes; + } + + void decrease_known_garbage_bytes(size_t known_garbage_bytes) { + guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" ); + + _known_garbage_bytes -= known_garbage_bytes; + size_t heap_bytes = _g1->capacity(); + _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes; + } + + G1MMUTracker* mmu_tracker() { + return _mmu_tracker; + } + + double predict_init_time_ms() { + return get_new_prediction(_concurrent_mark_init_times_ms); + } + + double predict_remark_time_ms() { + return get_new_prediction(_concurrent_mark_remark_times_ms); + } + + double predict_cleanup_time_ms() { + return get_new_prediction(_concurrent_mark_cleanup_times_ms); + } + + // Returns an estimate of the survival rate of the region at yg-age + // "yg_age". + double predict_yg_surv_rate(int age) { + TruncatedSeq* seq = _short_lived_surv_rate_group->get_seq(age); + if (seq->num() == 0) + gclog_or_tty->print("BARF! age is %d", age); + guarantee( seq->num() > 0, "invariant" ); + double pred = get_new_prediction(seq); + if (pred > 1.0) + pred = 1.0; + return pred; + } + + double accum_yg_surv_rate_pred(int age) { + return _short_lived_surv_rate_group->accum_surv_rate_pred(age); + } + +protected: + void print_stats (int level, const char* str, double value); + void print_stats (int level, const char* str, int value); + void print_par_stats (int level, const char* str, double* data) { + print_par_stats(level, str, data, true); + } + void print_par_stats (int level, const char* str, double* data, bool summary); + void print_par_buffers (int level, const char* str, double* data, bool summary); + + void check_other_times(int level, + NumberSeq* other_times_ms, + NumberSeq* calc_other_times_ms) const; + + void print_summary (PauseSummary* stats) const; + void print_abandoned_summary(PauseSummary* non_pop_summary, + PauseSummary* pop_summary) const; + + void print_summary (int level, const char* str, NumberSeq* seq) const; + void print_summary_sd (int level, const char* str, NumberSeq* seq) const; + + double avg_value (double* data); + double max_value (double* data); + double sum_of_values (double* data); + double max_sum (double* data1, double* data2); + + int _last_satb_drain_processed_buffers; + int _last_update_rs_processed_buffers; + double _last_pause_time_ms; + + size_t _bytes_in_to_space_before_gc; + size_t _bytes_in_to_space_after_gc; + size_t bytes_in_to_space_during_gc() { + return + _bytes_in_to_space_after_gc - _bytes_in_to_space_before_gc; + } + size_t _bytes_in_collection_set_before_gc; + // Used to count used bytes in CS. + friend class CountCSClosure; + + // Statistics kept per GC stoppage, pause or full. + TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec; + + // We track markings. + int _num_markings; + double _mark_thread_startup_sec; // Time at startup of marking thread + + // Add a new GC of the given duration and end time to the record. + void update_recent_gc_times(double end_time_sec, double elapsed_ms); + + // The head of the list (via "next_in_collection_set()") representing the + // current collection set. + HeapRegion* _collection_set; + size_t _collection_set_size; + size_t _collection_set_bytes_used_before; + + // Info about marking. + int _n_marks; // Sticky at 2, so we know when we've done at least 2. + + // The number of collection pauses at the end of the last mark. + size_t _n_pauses_at_mark_end; + + // ==== This section is for stats related to starting Conc Refinement on time. + size_t _conc_refine_enabled; + size_t _conc_refine_zero_traversals; + size_t _conc_refine_max_traversals; + // In # of heap regions. + size_t _conc_refine_current_delta; + + // At the beginning of a collection pause, update the variables above, + // especially the "delta". + void update_conc_refine_data(); + // ==== + + // Stash a pointer to the g1 heap. + G1CollectedHeap* _g1; + + // The average time in ms per collection pause, averaged over recent pauses. + double recent_avg_time_for_pauses_ms(); + + // The average time in ms for processing CollectedHeap strong roots, per + // collection pause, averaged over recent pauses. + double recent_avg_time_for_CH_strong_ms(); + + // The average time in ms for processing the G1 remembered set, per + // pause, averaged over recent pauses. + double recent_avg_time_for_G1_strong_ms(); + + // The average time in ms for "evacuating followers", per pause, averaged + // over recent pauses. + double recent_avg_time_for_evac_ms(); + + // The number of "recent" GCs recorded in the number sequences + int number_of_recent_gcs(); + + // The average survival ratio, computed by the total number of bytes + // suriviving / total number of bytes before collection over the last + // several recent pauses. + double recent_avg_survival_fraction(); + // The survival fraction of the most recent pause; if there have been no + // pauses, returns 1.0. + double last_survival_fraction(); + + // Returns a "conservative" estimate of the recent survival rate, i.e., + // one that may be higher than "recent_avg_survival_fraction". + // This is conservative in several ways: + // If there have been few pauses, it will assume a potential high + // variance, and err on the side of caution. + // It puts a lower bound (currently 0.1) on the value it will return. + // To try to detect phase changes, if the most recent pause ("latest") has a + // higher-than average ("avg") survival rate, it returns that rate. + // "work" version is a utility function; young is restricted to young regions. + double conservative_avg_survival_fraction_work(double avg, + double latest); + + // The arguments are the two sequences that keep track of the number of bytes + // surviving and the total number of bytes before collection, resp., + // over the last evereal recent pauses + // Returns the survival rate for the category in the most recent pause. + // If there have been no pauses, returns 1.0. + double last_survival_fraction_work(TruncatedSeq* surviving, + TruncatedSeq* before); + + // The arguments are the two sequences that keep track of the number of bytes + // surviving and the total number of bytes before collection, resp., + // over the last several recent pauses + // Returns the average survival ration over the last several recent pauses + // If there have been no pauses, return 1.0 + double recent_avg_survival_fraction_work(TruncatedSeq* surviving, + TruncatedSeq* before); + + double conservative_avg_survival_fraction() { + double avg = recent_avg_survival_fraction(); + double latest = last_survival_fraction(); + return conservative_avg_survival_fraction_work(avg, latest); + } + + // The ratio of gc time to elapsed time, computed over recent pauses. + double _recent_avg_pause_time_ratio; + + double recent_avg_pause_time_ratio() { + return _recent_avg_pause_time_ratio; + } + + // Number of pauses between concurrent marking. + size_t _pauses_btwn_concurrent_mark; + + size_t _n_marks_since_last_pause; + + // True iff CM has been initiated. + bool _conc_mark_initiated; + + // True iff CM should be initiated + bool _should_initiate_conc_mark; + bool _should_revert_to_full_young_gcs; + bool _last_full_young_gc; + + // This set of variables tracks the collector efficiency, in order to + // determine whether we should initiate a new marking. + double _cur_mark_stop_world_time_ms; + double _mark_init_start_sec; + double _mark_remark_start_sec; + double _mark_cleanup_start_sec; + double _mark_closure_time_ms; + + void calculate_young_list_min_length(); + void calculate_young_list_target_config(); + void calculate_young_list_target_config(size_t rs_lengths); + size_t calculate_optimal_so_length(size_t young_list_length); + +public: + + G1CollectorPolicy(); + + virtual G1CollectorPolicy* as_g1_policy() { return this; } + + virtual CollectorPolicy::Name kind() { + return CollectorPolicy::G1CollectorPolicyKind; + } + + void check_prediction_validity(); + + size_t bytes_in_collection_set() { + return _bytes_in_collection_set_before_gc; + } + + size_t bytes_in_to_space() { + return bytes_in_to_space_during_gc(); + } + + unsigned calc_gc_alloc_time_stamp() { + return _all_pause_times_ms->num() + 1; + } + +protected: + + // Count the number of bytes used in the CS. + void count_CS_bytes_used(); + + // Together these do the base cleanup-recording work. Subclasses might + // want to put something between them. + void record_concurrent_mark_cleanup_end_work1(size_t freed_bytes, + size_t max_live_bytes); + void record_concurrent_mark_cleanup_end_work2(); + +public: + + virtual void init(); + + virtual HeapWord* mem_allocate_work(size_t size, + bool is_tlab, + bool* gc_overhead_limit_was_exceeded); + + // This method controls how a collector handles one or more + // of its generations being fully allocated. + virtual HeapWord* satisfy_failed_allocation(size_t size, + bool is_tlab); + + BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; } + + GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; } + + // The number of collection pauses so far. + long n_pauses() const { return _n_pauses; } + + // Update the heuristic info to record a collection pause of the given + // start time, where the given number of bytes were used at the start. + // This may involve changing the desired size of a collection set. + + virtual void record_stop_world_start(); + + virtual void record_collection_pause_start(double start_time_sec, + size_t start_used); + + virtual void record_popular_pause_preamble_start(); + virtual void record_popular_pause_preamble_end(); + + // Must currently be called while the world is stopped. + virtual void record_concurrent_mark_init_start(); + virtual void record_concurrent_mark_init_end(); + void record_concurrent_mark_init_end_pre(double + mark_init_elapsed_time_ms); + + void record_mark_closure_time(double mark_closure_time_ms); + + virtual void record_concurrent_mark_remark_start(); + virtual void record_concurrent_mark_remark_end(); + + virtual void record_concurrent_mark_cleanup_start(); + virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes, + size_t max_live_bytes); + virtual void record_concurrent_mark_cleanup_completed(); + + virtual void record_concurrent_pause(); + virtual void record_concurrent_pause_end(); + + virtual void record_collection_pause_end_CH_strong_roots(); + virtual void record_collection_pause_end_G1_strong_roots(); + + virtual void record_collection_pause_end(bool popular, bool abandoned); + + // Record the fact that a full collection occurred. + virtual void record_full_collection_start(); + virtual void record_full_collection_end(); + + void record_ext_root_scan_time(int worker_i, double ms) { + _par_last_ext_root_scan_times_ms[worker_i] = ms; + } + + void record_mark_stack_scan_time(int worker_i, double ms) { + _par_last_mark_stack_scan_times_ms[worker_i] = ms; + } + + void record_scan_only_time(int worker_i, double ms, int n) { + _par_last_scan_only_times_ms[worker_i] = ms; + _par_last_scan_only_regions_scanned[worker_i] = (double) n; + } + + void record_satb_drain_time(double ms) { + _cur_satb_drain_time_ms = ms; + _satb_drain_time_set = true; + } + + void record_satb_drain_processed_buffers (int processed_buffers) { + _last_satb_drain_processed_buffers = processed_buffers; + } + + void record_mod_union_time(double ms) { + _all_mod_union_times_ms->add(ms); + } + + void record_update_rs_start_time(int thread, double ms) { + _par_last_update_rs_start_times_ms[thread] = ms; + } + + void record_update_rs_time(int thread, double ms) { + _par_last_update_rs_times_ms[thread] = ms; + } + + void record_update_rs_processed_buffers (int thread, + double processed_buffers) { + _par_last_update_rs_processed_buffers[thread] = processed_buffers; + } + + void record_scan_rs_start_time(int thread, double ms) { + _par_last_scan_rs_start_times_ms[thread] = ms; + } + + void record_scan_rs_time(int thread, double ms) { + _par_last_scan_rs_times_ms[thread] = ms; + } + + void record_scan_new_refs_time(int thread, double ms) { + _par_last_scan_new_refs_times_ms[thread] = ms; + } + + double get_scan_new_refs_time(int thread) { + return _par_last_scan_new_refs_times_ms[thread]; + } + + void reset_obj_copy_time(int thread) { + _par_last_obj_copy_times_ms[thread] = 0.0; + } + + void reset_obj_copy_time() { + reset_obj_copy_time(0); + } + + void record_obj_copy_time(int thread, double ms) { + _par_last_obj_copy_times_ms[thread] += ms; + } + + void record_obj_copy_time(double ms) { + record_obj_copy_time(0, ms); + } + + void record_termination_time(int thread, double ms) { + _par_last_termination_times_ms[thread] = ms; + } + + void record_termination_time(double ms) { + record_termination_time(0, ms); + } + + void record_pause_time(double ms) { + _last_pause_time_ms = ms; + } + + void record_clear_ct_time(double ms) { + _cur_clear_ct_time_ms = ms; + } + + void record_par_time(double ms) { + _cur_collection_par_time_ms = ms; + } + + void record_aux_start_time(int i) { + guarantee(i < _aux_num, "should be within range"); + _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0; + } + + void record_aux_end_time(int i) { + guarantee(i < _aux_num, "should be within range"); + double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i]; + _cur_aux_times_set[i] = true; + _cur_aux_times_ms[i] += ms; + } + + void record_pop_compute_rc_start(); + void record_pop_compute_rc_end(); + + void record_pop_evac_start(); + void record_pop_evac_end(); + + // Record the fact that "bytes" bytes allocated in a region. + void record_before_bytes(size_t bytes); + void record_after_bytes(size_t bytes); + + // Returns "true" if this is a good time to do a collection pause. + // The "word_size" argument, if non-zero, indicates the size of an + // allocation request that is prompting this query. + virtual bool should_do_collection_pause(size_t word_size) = 0; + + // Choose a new collection set. Marks the chosen regions as being + // "in_collection_set", and links them together. The head and number of + // the collection set are available via access methods. + // If "pop_region" is non-NULL, it is a popular region that has already + // been added to the collection set. + virtual void choose_collection_set(HeapRegion* pop_region = NULL) = 0; + + void clear_collection_set() { _collection_set = NULL; } + + // The head of the list (via "next_in_collection_set()") representing the + // current collection set. + HeapRegion* collection_set() { return _collection_set; } + + // Sets the collection set to the given single region. + virtual void set_single_region_collection_set(HeapRegion* hr); + + // The number of elements in the current collection set. + size_t collection_set_size() { return _collection_set_size; } + + // Add "hr" to the CS. + void add_to_collection_set(HeapRegion* hr); + + bool should_initiate_conc_mark() { return _should_initiate_conc_mark; } + void set_should_initiate_conc_mark() { _should_initiate_conc_mark = true; } + void unset_should_initiate_conc_mark(){ _should_initiate_conc_mark = false; } + + void checkpoint_conc_overhead(); + + // If an expansion would be appropriate, because recent GC overhead had + // exceeded the desired limit, return an amount to expand by. + virtual size_t expansion_amount(); + + // note start of mark thread + void note_start_of_mark_thread(); + + // The marked bytes of the "r" has changed; reclassify it's desirability + // for marking. Also asserts that "r" is eligible for a CS. + virtual void note_change_in_marked_bytes(HeapRegion* r) = 0; + +#ifndef PRODUCT + // Check any appropriate marked bytes info, asserting false if + // something's wrong, else returning "true". + virtual bool assertMarkedBytesDataOK() = 0; +#endif + + // Print tracing information. + void print_tracing_info() const; + + // Print stats on young survival ratio + void print_yg_surv_rate_info() const; + + void finished_recalculating_age_indexes() { + _short_lived_surv_rate_group->finished_recalculating_age_indexes(); + // do that for any other surv rate groups + } + + bool should_add_next_region_to_young_list(); + + bool in_young_gc_mode() { + return _in_young_gc_mode; + } + void set_in_young_gc_mode(bool in_young_gc_mode) { + _in_young_gc_mode = in_young_gc_mode; + } + + bool full_young_gcs() { + return _full_young_gcs; + } + void set_full_young_gcs(bool full_young_gcs) { + _full_young_gcs = full_young_gcs; + } + + bool adaptive_young_list_length() { + return _adaptive_young_list_length; + } + void set_adaptive_young_list_length(bool adaptive_young_list_length) { + _adaptive_young_list_length = adaptive_young_list_length; + } + + inline double get_gc_eff_factor() { + double ratio = _known_garbage_ratio; + + double square = ratio * ratio; + // square = square * square; + double ret = square * 9.0 + 1.0; +#if 0 + gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret); +#endif // 0 + guarantee(0.0 <= ret && ret < 10.0, "invariant!"); + return ret; + } + + // + // Survivor regions policy. + // +protected: + + // Current tenuring threshold, set to 0 if the collector reaches the + // maximum amount of suvivors regions. + int _tenuring_threshold; + +public: + + inline GCAllocPurpose + evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) { + if (age < _tenuring_threshold && src_region->is_young()) { + return GCAllocForSurvived; + } else { + return GCAllocForTenured; + } + } + + inline bool track_object_age(GCAllocPurpose purpose) { + return purpose == GCAllocForSurvived; + } + + inline GCAllocPurpose alternative_purpose(int purpose) { + return GCAllocForTenured; + } + + uint max_regions(int purpose); + + // The limit on regions for a particular purpose is reached. + void note_alloc_region_limit_reached(int purpose) { + if (purpose == GCAllocForSurvived) { + _tenuring_threshold = 0; + } + } + + void note_start_adding_survivor_regions() { + _survivor_surv_rate_group->start_adding_regions(); + } + + void note_stop_adding_survivor_regions() { + _survivor_surv_rate_group->stop_adding_regions(); + } +}; + +// This encapsulates a particular strategy for a g1 Collector. +// +// Start a concurrent mark when our heap size is n bytes +// greater then our heap size was at the last concurrent +// mark. Where n is a function of the CMSTriggerRatio +// and the MinHeapFreeRatio. +// +// Start a g1 collection pause when we have allocated the +// average number of bytes currently being freed in +// a collection, but only if it is at least one region +// full +// +// Resize Heap based on desired +// allocation space, where desired allocation space is +// a function of survival rate and desired future to size. +// +// Choose collection set by first picking all older regions +// which have a survival rate which beats our projected young +// survival rate. Then fill out the number of needed regions +// with young regions. + +class G1CollectorPolicy_BestRegionsFirst: public G1CollectorPolicy { + CollectionSetChooser* _collectionSetChooser; + // If the estimated is less then desirable, resize if possible. + void expand_if_possible(size_t numRegions); + + virtual void choose_collection_set(HeapRegion* pop_region = NULL); + virtual void record_collection_pause_start(double start_time_sec, + size_t start_used); + virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes, + size_t max_live_bytes); + virtual void record_full_collection_end(); + +public: + G1CollectorPolicy_BestRegionsFirst() { + _collectionSetChooser = new CollectionSetChooser(); + } + void record_collection_pause_end(bool popular, bool abandoned); + bool should_do_collection_pause(size_t word_size); + virtual void set_single_region_collection_set(HeapRegion* hr); + // This is not needed any more, after the CSet choosing code was + // changed to use the pause prediction work. But let's leave the + // hook in just in case. + void note_change_in_marked_bytes(HeapRegion* r) { } +#ifndef PRODUCT + bool assertMarkedBytesDataOK(); +#endif +}; + +// This should move to some place more general... + +// If we have "n" measurements, and we've kept track of their "sum" and the +// "sum_of_squares" of the measurements, this returns the variance of the +// sequence. +inline double variance(int n, double sum_of_squares, double sum) { + double n_d = (double)n; + double avg = sum/n_d; + return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d; +} + +// Local Variables: *** +// c-indentation-style: gnu *** +// End: ***